equivalent | 易学教程

How would you do the equivalent of preprocessor directives in Python?

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问题 Is there a way to do the following preprocessor directives in Python? #if DEBUG < do some code > #else < do some other code > #endif 回答1: There's __debug__ , which is a special value that the compiler does preprocess. if __debug__: print "If this prints, you're not running python -O." else: print "If this prints, you are running python -O!" __debug__ will be replaced with a constant 0 or 1 by the compiler, and the optimizer will remove any if 0: lines before your source is interpreted. 回答2: I

Is there a python equivalent of Ruby's 'rvm'?

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问题 Q: Do we have anything functionally equivalent in Python to the Ruby version manager 'rvm'? ( RVM lets you easily switch completely between different versions of the ruby interpreter and different sets of gems (modules). Everything concerning download-build-install-switch of interpreter(-s) and gems gets taken care of by invoking rvm. It is all run under your regular user account.) 回答1: Yes, it is virtualenv along with virtualenvwrapper. update: you may install both at once with virtualenv

What is the equivalent of memset in C#?

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I need to fill a byte[] with a single non-zero value. How can I do this in C# without looping through each byte in the array? Update: The comments seem to have split this into two questions - Is there a Framework method to fill a byte[] that might be akin to memset What is the most efficient way to do it when we are dealing with a very large array? I totally agree that using a simple loop works just fine, as Eric and others have pointed out. The point of the question was to see if I could learn something new about C# :) I think Juliet's method for a Parallel operation should be even faster

is there a Java equivalent to null coalescing operator (??) in C#? [duplicate]

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问题 This question already has answers here : How to get the first non-null value in Java? (12 answers) Closed 2 years ago . Is it possible to do something similar to the following code in Java int y = x ?? -1; More about ?? 回答1: Sadly - no. The closest you can do is: int y = (x != null) ? x : -1; Of course, you can wrap this up in library methods if you feel the need to (it's unlikely to cut down on length much), but at the syntax level there isn't anything more succinct available. 回答2: Guava has

What is the equivalent of the Java BigDecimal class in C#?

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BigDecimal is a class in the java.math package that has a lot of benefits for handling big numbers of a certain scale. Is there an equivalent class or data type in c# with this feature. C# only has BigInteger built it (in .NET framework 4). Is decimal enough precision for your task? It's a 128-bit number that can hold values in the range ±1.0 × 10 −28 to ±7.9 × 10 28 . Just recently I also needed an arbitrary precision decimal in C# and came across the idea posted here: https://stackoverflow.com/a/4524254/804614 I then completed the draft to support all basic arithmetic and comparison

XSLT equivalent for JSON [closed]

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问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 months ago . Is there an XSLT equivalent for JSON? Something to allow me to do transformations on JSON like XSLT does to XML. 回答1: Interesting idea. Some searching on Google produced a few pages of interest, including: an outline of how such a "jsonT" tool might be implemented, and some downloads some discussion of that

What is the equivalent of memset in C#?

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问题 I need to fill a byte[] with a single non-zero value. How can I do this in C# without looping through each byte in the array? Update: The comments seem to have split this into two questions - Is there a Framework method to fill a byte[] that might be akin to memset What is the most efficient way to do it when we are dealing with a very large array? I totally agree that using a simple loop works just fine, as Eric and others have pointed out. The point of the question was to see if I could

What is the equivalent of the Java BigDecimal class in C#?

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问题 BigDecimal is a class in the java.math package that has a lot of benefits for handling big numbers of a certain scale. Is there an equivalent class or data type in c# with this feature. 回答1: C# only has BigInteger built it (in .NET framework 4). Is decimal enough precision for your task? It's a 128-bit number that can hold values in the range ±1.0 × 10 −28 to ±7.9 × 10 28 . 回答2: Just recently I also needed an arbitrary precision decimal in C# and came across the idea posted here: https:/